Artificial respirator



April 1940' J. H. EMERSON ARTIFICIAL RESPIRATOR Filed DEC. 26, 1939 mania? J6 m' 5 7v M? Patented Apr. 2, 1940 PATENT OFFICE ARTIFICIAL RESPIRATOR John H. Emerson, Cambridge, Mass.

Application December 26, 1939, Serial No. 310,868

3 Claims.

This invention relates .to artificial respirators for stimulating breathing in persons suffering from infantile paralysis, drowning, suffocation, etc., and more particularly to a safety alarm for such a respirator. The artificial respirator to which the invention relates comprises an air tight casing which encloses the chest of the patient, leaving at least his nose and mouth exposed to the atmosphere. Alternate negative and atmospheric or positive pressures are created within the casing in time with the normal respiration periods of the patient. Each negative'pressure period causes the patient's chest and lungs to expand and air is automatically drawn into his lungs through his nose and mouth thereby causing an inhalation. Each atmospheric or positive pressure period causes the patient's chest to collapse forcing the air in his lungs to be expelled through his nose and mouth and thus causing an exhalation.

The casing may be large enough to enclose the patient's entire body with the exception of his head, or it may only be large enough to enclose his chest. Reference may be had to United States Letters Patent No. 1,834,580 and No. 2,060,706 for more detailed description of a suitable respirator.

The pressure variations within the respirator may vary from twelve to sixty per minute. The usual degree of negative pressure during each negative pressure period for an average patient is from five to fifteen centimeters of water. Ordinarily the pressure is alternated from negative to atmospheric, but in cases where there is a lack of tone in the chest muscles the pressure is alternated from negative to positive.

In cases of infantile paralysis it is frequently necessary to keep the patient in the respirator and to continue the treatment uninterruptedly for many days. The patient, being weak and unable to breath of his own accord, is unable to summon help when the respirator fails, which means that unless an attendant is present when the respirator fails the patient will die of suffocation.

It is the object of this invention to provide an artificial respirator with a safety alarm which will summon an attendant when the pressures within the respirator discontinue alternation.

Other objects relate to the construction and mode of operation and will be apparent from consideration of the following description and accompanying drawing which exemplify one embodiment of my invention chosen for the purposes of illustration.

In the drawing Fig. 1 is a side elevation of an artificial respirator embodying my invention;

Fig. 2 is an enlarged plan view of the safety alarm;

Fig. 3 is an enlarged partial section taken on the lines 33 of Fig. 2;

Fig. 4 is a section taken on the lines 44 of Fig. 3;

Fig. 5 is a wiring diagram for the safety alarm.

The respirator illustrated comprises a wheel carriage ill on which is mounted the rigid respirator casing II which forms the enclosure for the patient's body up to his neck. The patient reclines upon the bed i2, his neck extending through a restricted orifice in the end l3 of the casing and his head resting upon the support 14. The end I3 of the casing is held in removable air tight position by means of the releasable clamp A collapsible diaphragm or bellows i6 forms the other end of the casing II. The bellows i6 is operated by the arm i'I pivotally secured at l8 to the fixed mounting IS, the arm II having its lower end pivotally secured at 20 to the connecting rod 5i. The connecting rod Si is reciprocated horizontally by a motor (not shown) thereby actuating the arm I! to move the diaphragm I6 into and out of the casing ii. In the position shown in Fig. 1 the diaphragm being outside of the casing, negative pressure has been created within the casing; as the arm I! is moved counter-clockwise about the pivot I8 the diaphragm is forced within the end of the casing thereby releasing the negative pressure and creating either atmospheric or positive pressure as desired. The duration of each period of negative and atmospheric or positive pressure may be varied at will by a suitable attachment associated either with the connecting rod Si or the means which drives it.

The safety alarm 2| comprises a metal housing 22 containing dry cell batteries 23, an electric bell 24 (not fully shown) and a metallic casing 25. The housing 22 is removably secured to the respirator casing I i (see Fig. 3) by the exteriorly threaded housing flange 33 which fits within the interiorly threaded respirator flange 34.

A substantially air-tight alarm chamber 26 (Fig. 3) is provided by the resilient metallic bellows wall 21 having an upper wall 28 sealed to the upper end thereof and by the lower part of the casing which is made a part of the chamber 26 by the bracket 29 which extends around the interior of the casing 25 and is sealed thereto and to the lower end of the bellows wall 21. The

bellows wall 21 is normally extended longitudinally but may be collapsed to the position shown in Fig. 3 thereby moving the upper wall 28 away from the top of the casing 25 so that the wall 28 may be considered a movable wall of the alarm chamber.

A passage 30 (Fig. 3) provides communication between the alarm chamber 26 and the interior of the respirator casing The passage 30 passes through the bottom of the casing 25, through the adjacent portion of the housing 22, through the center of the valve seat member 3|, and through the center of the valve retaining member 32. The valve seat member 3| is exteriorly threaded and fits within the adjacent interiorly threaded portion of the valve retaining member 32 thereby being removably secured thereto.

A pneumatically operated valve 35 is normally held in engagement with the lower end 36 of the valve seat member 3| by the coil spring 38, the lower end of which rests upon an abutment 33 provided within the valve retaining member 32. Upon creation of negative pressure within the respirator casing H the valve 35 is moved downwardly against the pressure of the spring 38 and the passage 30 is open thereby permitting negative pressure from the respirator casing to pass to the interior of the alarm chamber 26, the negative pressure in the alarm chamber 26 causing the movable wall 28 to move downwardly against the resilience of the bellows wall 21 to the position shown in Fig. 3.

A series of perforations 40 is provided in the casing 25 (Fig. 4) A slide 4| is mounted for sliding movement upon the casing 25 by means of the members 42. A handle 43 is secured to the slide 4| and extends outwardly through a slot 44 in the housing 22. Said perforations 40 and slide 4| provide an adjustable communication between the interior of the alarm chamber 26 and the atmosphere, to permit a restricted and substantially constant flow of atmospheric pressure to the interior of the alarm chamber. It will be noted that the perforations 40 are substantially smaller than the passage 30. The slide 4| may be actuated to open a plurality of said perforations or to close all but one.

An electrical contact 45 is insulated from the casing 25 and is electrically connected in series to an electric alarm circuit in which the electric bell 24 is the alarm. Another contact 46 is provided upon the movable wall 28 and is also connected to the alarm circuit. The alarm circuit is energized by the batteries 23 and the circuit may only be closed when the contact 46 engages the contact 45. A manually operated switch 41 is also operable to open and close the alarm circuit when the contacts 45 and 46 are in engagement.

In operation when the patient has been inserted in the casing II and the diaphragm |6 placed in operation, the switch 41 is closed and is left closed continuously during operation. The diaphragm l6 creates negative pressure in the casing l which opens the valve 35, creates negative pressure in the alarm chamber 26 which negative pressure causes the wall 28 to move downwardly, thus separating the contacts 46 and 45 and opening the alarm circuit. The valve 35 closes during each period of atmospheric or positive presure within the casing I and is reopened during each period of negative pressure within the casing, and the slide 4| is adjusted so that the operative perforation or perforations 40 is or are small enough so that they do not permit the amount of atmospheric pressure admitted to the alarm chamber during each alternate period of positive or atmospheric pressure in the respirator casing H to counteract the negative pressure in the alarm chamber so that the movable wall 28 remains lowered and the alarm circuit remains open as long as the pressures within the resiprator casing are alternated. As soon as those alternations cease, however. the valve 35 continues to remain closed and the operative perforation or perforations 40 continue to admit atmospheric pressure to the alarm chamber and this causes the pressure within the alarm chamber to be raised from negative to atmospheric pressure, thereby causing the wall 28 to be elevated thereby closing the alarm circuit and causing the bell 24 to ring. The bell will continue to ring until an attendant either turns off the switch 41 or causes the alternate pressures to be resumed within the casing The valve 35 and spring 38 may be reversed so that the valve is opened by positive pressure in the respirator and closed by negative pressure. In such a construction the bellows 21, its movable wall 28 and the contacts 45, 46 are arranged so that the maintenance of positive pressure in the alarm chamber 26 will separate the contacts and the presence of atmospheric pressure therein will cause them to engage. For such an arrangement (referring to Fig. 3) the bracket 29 may be placed near the top of the cylinder 25 and the upper end of the bellows wall 21 sealed thereto; the movable wall 28 would then be sealed to the suspended bottom end of the wall 21 with its contact 46 facing downwardly and the contact 45 would then be mounted in fixed position below the contact 46. Under atmospheric pressure in the alarm chamber the wall 21 would be in normally expanded position and the movable wall 28 would be at its normal lowermost position wherein the contacts would engage each other to close the alarm circuit. When positive pressure is created in the respirator and correspondingly in the alarm chamber the movable wall 28 would rise and maintain the alarm circuit open until atmospheric pressure is restored to the alarm chamber. Such a construction would be usable when pressures in the respirator are alternated from positive to atmospheric or negative.

While I have shown and described two desirable embodiments of the invention it is to be understood that this disclosure is for the purpose of illustration and that various changes in shape, proportion and arrangement of parts and the substitution of equivalent elements may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive the patients chest, means for producing alternate negative and atmospheric or positive pressures within said casing, and a safety alarm comprising a substantially air-tight alarm chamber having a pneumatically movable wall portion, an electric alarm circuit adapted to be closed by movement of said wall portion to a given position, a passage connecting said alarm chamber with the interior of said respirator casing, a pneumatically operable valve associated with said passage, and means communicating with said alarm chamber to permit a restricted and substantially constant flow of atmospheric pressure thereto, said valve and said latter means being constructed and arranged to maintain the n pressure within said alarm chamber to cause said movable wall portion to remain in a position wherein said alarm circuit is open when the pressures within the respirator casing are alternated and to maintain the necessary pressure within said alarm chamber to cause said movable wall portion to remain in a position wherein said alarm circuit is closed when the pressures within the respirator casing discontinue alternation.

2. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive the patient's chest, means for producing alternate negative and atmospheric or positive pressures within said casing, and a safety alarm comprising a substantially air-tight alarm chamber having a pneumatically movable wall portion, an electric alarm circuit adapted to be closed by movement of said wall portion to a given position, a passage connectins said alarm chamber with the interior of said respirator casing, a pneumatically operable valve normally closing said passage and operable to open said passage when negative pressure is created in the respirator casing, and means communicating with said alarm chamber to permit a restricted and substantially constant flow of atmospheric pressure thereto, said valve and said latter means being constructed and arranged to maintain negative pressure in said alarm chamber when the pressures within the respirator casing are alternated, and to restore the pressure in said alarm casing to atmospheric pressure when the pressures within the respirator casing discontinue alternation, said movable wall portion moving to circuit closing position upon the creation of atmospheric pressure within the alarm chamber and moving to circuit-opening position upon the creation 0! negative pressure within the alarm chamber.

3. Apparatus for producing artificial respiration comprising a substantially air-tight respirator casing to receive the patient's chest, means for producing alternate negative and positive pressures within said casing, and a safety alarm comprising a substantially air-tight alarm chamber having a pneumatically movable wall portion, an electric alarm circuit adapted to be closed by movement of said wall portion to a given position, a passage connecting said alarm chamber with the interior of said respirator casing, a pneumatically operable valve normally closing said passage and operable to open said passage when positive pressure is created in the respirator casing, and means communicating with said alarm chamber to permit a restricted and substantially constant flow of atmospheric pressure thereto, said valve and said latter means being constructed and arranged to maintain positive pressure in said alarm chamber when the pressures within the respirator casing are alternated, and to restore the pressure in said alarm chamber to atmospheric pressure when the pressures within the respirator casing discontinue alternatlon, said movable wall portion moving to circuit closing position upon the creation of atmospheric pressure within the alarm chamber and moving to circuit opening position upon the creation of positive pressure within the alarm chamber.

JOHN H. EMERSON. j 

